Here, you are looking at the Hi-power Spec-R Catback Exhaust for your 2002-2007 WRX/STI. 

High-quality sound. Sports exhaust system with reduced noise level.Silent Hi-Power mufflers offer high performance and sporty appearance with the added benefit of reduced noise levels making it the best choice for more mature enthusiasts. Silent Hi-Power mufflers are constructed entirely of SUS304 grade stainless steel for high luster, long-lasting performance. For certain applications, HKS has introduced the "Silent Chamber" which removes a lot of the lower frequency noise that can often be heard into the cabin even when cruising. The silent chamber removes this uncomfortable noise but due to its closed-end design, only a minimal amount of exhaust gas flows into it, meaning that the disruption to exhaust gas flow through the entire system is minimized and there is no harm to performance.

Details:

• 120mm Polished Tip
• 92 Decibels 
• "JASMA" approved.
• SUS304 for improvement of appearance and durability.
• Proven "Advantex* glass wool" (Continuous fiber glass wool).
• Hollow hook and pressed flange for some vehicles to reduce weight.
• The redesigned inner structure of silencer to improve performance and appearance.

Note: A OEM Downpipe to 3in Cat Back Adapter may be necessary if the diameter of the new cat-back exhaust systems piping is different from the stock system, or if there are compatibility issues between the new components and the existing downpipe.